Blue Ocean Institute


Some problems exist with this species' status or catch methods, or information is insufficient for evaluating. Tuna, Southern Bluefin – Longline (Minamimaguro, Honmaguro) These fish contain levels of mercury or PCBs that may pose a health risk to adults and children.

Southern Bluefin Tuna have been over exploited for decades and the current abundance is very low. They have a high value on the Japanese sashimi market, where they are often used interchangeably with other Bluefin Tunas. Japan has the largest longline fleet targeting Southern Bluefin Tuna.  The percentage of the catch taken by longlines has decreased from about 80% in 1980 to about 50% today.

Southern Bluefin Tunas inhabit the cold waters of the southern Pacific, Indian and Atlantic Oceans, with the majority caught in the Indian Ocean. Spawning occurs southeast of Java in the Indian Ocean, where Southern Bluefin tunas release millions of eggs per spawning event. Southern Bluefin Tunas do not reach sexual maturity until at least eight years of age and can reach approximately 8 feet and weight up to 572 pounds.

Full species report here.

This fish may have high levels of mercury that could pose a health risk to adults and children. More info here about mercury in tuna. Check out our mercury in seafood section.